Next-to-leading order QCD corrections to the lifetime difference of B(s) mesons.

In this talk we present a calculation of the dacay rate difference in the neutral Bs − Bs system, ????Bs , in next-to-leading order (NLO) QCD. We find a sizeable decrease compared to leading- order (LO) estimates: (????/????)Bs = (fBs/210MeV )2[0.006B(mb)+0.150BS(mb)−0.0063] in terms of the bag parameters B and BS in the NDR scheme. We put special emphasize on the theoretical and physical implications of this quantity